[PULL,v2,79/86] virtio-net: setup vhost_dev and notifiers for cvq only when feature is negotiated

Commit Message

Michael S. Tsirkin May 16, 2022, 8:55 p.m. UTC

From: Si-Wei Liu <[e-mail]>

When the control virtqueue feature is absent or not negotiated,
vhost_net_start() still tries to set up vhost_dev and install
vhost notifiers for the control virtqueue, which results in
erroneous ioctl calls with incorrect queue index sending down
to driver. Do that only when needed.

Fixes: 22288fe ("virtio-net: vhost control virtqueue support")
Signed-off-by: Si-Wei Liu <[e-mail]>
Acked-by: Jason Wang <[e-mail]>
Message-Id: <[e-mail]>
Reviewed-by: Michael S. Tsirkin <[e-mail]>
Signed-off-by: Michael S. Tsirkin <[e-mail]>
---
 hw/net/virtio-net.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Patch

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index a788f1c5c7..7545a16ed7 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -245,7 +245,8 @@  static void virtio_net_vhost_status(VirtIONet *n, uint8_t status)
     VirtIODevice *vdev = VIRTIO_DEVICE(n);
     NetClientState *nc = qemu_get_queue(n->nic);
     int queue_pairs = n->multiqueue ? n->max_queue_pairs : 1;
-    int cvq = n->max_ncs - n->max_queue_pairs;
+    int cvq = virtio_vdev_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ) ?
+              n->max_ncs - n->max_queue_pairs : 0;
 
     if (!get_vhost_net(nc->peer)) {
         return;